feat!: add User SSH config directive when creating config entry

Specifying the User in the topo_config when adding a new config entry
allows for better detection of conflicting users:

`topo setup-keys --target <ip>` will generate SSH key files for the
default user.

We are already demanding a per-user alias. Might as well enforce it.

Signed-off-by: Tomás González <[email protected]>

Author: tgonzalezorlandoarm

cmd/topo/setup_keys.go

@@ -65,6 +65,7 @@ var setupKeysCmd = &cobra.Command{
 		modifiers := []ssh.ConfigDirectiveModifier{
 			ssh.NewEnsureConfigDirectivePath("IdentityFile", privateKeyPath),
 			ssh.NewEnsureConfigDirective("IdentitiesOnly", "yes"),
+			ssh.NewEnsureConfigDirective("User", dest.User),
 		}
 
 		return ssh.CreateOrModifyConfigFile(dest, modifiers)